Physicians' resources > Classification

Classification

In 1988, the International Headache Society (IHS) issued a detailed and structured classification of headaches and their respective diagnostic criteria. In 2004, the IHS produced a well thought-out revision of this classification. The so-called International Classification of Headache Disorders 2nd Edition (ICHD-II) was officially presented at the XI International Headache Congress in Rome in 2003 and was recently published in Cephalalgia (Cephalalgia 2004;24suppl1:1-160).

Fourteen groups of headaches are included in ICHD-II at the one-digit diagnostic level. These are categorised as follows:

  • Primary headaches: groups 1 to 4
  • Secondary headaches: groups 5 to 12
  • Cranial neuralgias, central and primary facial pain and other headaches: groups 13 and 14

ICHD-II adds an appendix, which in addition to describing a number of orphan disorders that need validation, also proposes a few alternative criteria that can be tested against the official ones.

General characteristics

  1. Hierarchical organisation: major groups (e.g., other primary headaches - code 4), types (e.g., primary headache associated with sexual activity - code 4.4), subtypes (e.g., preorgasmic headache - code 4.4.1), subforms (only for group 8; e.g., immediate NO donor-induced headache - code 8.1.1.1).
  2. Applicable at different healthcare levels: GPs need to diagnose at the first level, neurologists and headache specialists would normally diagnose the precise subtype.
  3. Classification of attacks and not of syndromes.
  4. Symptom-based classification of the primary headaches, aetiological classification of the secondary headaches.

1988 IHS classification vs ICHD-II: changes

Migraine group

  1. The new classification of migraine with aura recognises two separate forms based on the characterisation of the headache - i.e., with or without clinical features comparable to those of migraine without aura - and reconsiders the diagnostic criteria of aura - whose duration cannot be less than 5 minutes.
  2. Addition of sporadic form of hemiplegic migraine.
  3. Addition of cyclical vomiting and abdominal migraine in the group of child periodic syndromes that are commonly precursors of migraine.
  4. Addition among the "complications of migraine", of chronic migraine (code 1.5.1), persistent aura without infarction (code 1.5.3), migraine-triggered seizure (code 1.5.5).
  5. Ophthalmoplegic migraine is now coded 13.17 among the "cranial neuralgias, central and primary facial pain and other headaches";
  6. Alternating hemiplegia of childhood has been moved to the Appendix.

Tension-type headache group

  1. Distinction between two different subtypes of the episodic form, which are termed infrequent and frequent depending on whether they recur less or more often than once a month. The infrequent subtype has very little impact on the individual and does not deserve much attention from the medical profession.
  2. Manual palpation is indicated to detect pericranial tenderness. Data from EMG surface or pressure algometry are useless.

Cluster headache and other trigeminal autonomic cephalalgias

  1. Inclusion of episodic paroxysmal hemicrania.
  2. Inclusion of short lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT).
  3. Disappearance of the criterion "cluster headache periodicity undetermined".
  4. Disappearance of the division of chronic cluster headache into primary and secondary forms.
  5. Addition of sense of restlessness and of agitation as pain accompanying signs and symptoms to the diagnostic criteria for cluster headache.

Other primary headaches

  1. Addition of hypnic headache.
  2. Addition of primary thunderclap headache.
  3. Addition of hemicrania continua.
  4. Addition of new daily persistent headache (NDPH).
  5. External compression headache and cold stimulus headache are now coded to 13.10 and 13.11 among the "cranial neuralgias, central and primary facial pain and other headaches".
  6. Disappearance of the postural type of headache associated with sexual activity.

Finally, a comment on Group 12 of headache attributed to psychiatric disorder, which was not included in the 1988 version of the IHS classification. This is certainly an interesting addition, but the fact that ICHD-II includes only two forms of this headache - headache attributed to somatisation disorder and headache attributed to psychotic disorder - while indulging in lengthy comments and remarks, says a lot about the uncertainty still surrounding this group of headaches.

This page last modified: 06/04/2005